I am trying to generate random numbers that are used to generate a part of a world (I am working on world generation for a game). I could create these with something like [random.randint(0, 100) for n in range(1000)] to generate 1000 random numbers from 0 to 100, but I don't know how many numbers in a list I need. What I want is to be able to say something like random.nth_randint(0, 100, 5) which would generate the 5th random number from 0 to 100. (The same number every time as long as you use the same seed) How would I go about doing this? And if there is no way to do this, how else could I get the same behavior?
Python's random module produces deterministic pseudo random values.
In simpler words, it behaves as if it generated a list of predetermined values when a seed is provided (or when default seed is taken from OS), and those values will always be the same for a given seed. Which is basically what we want here.
So to get nth random value you need to either remember its state for each generated value (probably just keeping track of the values would be less memory hungry) or you need to reset (reseed) the generator each time and produce N random numbers each time to get yours.
def randgen(a, b, n, seed=4):
# our default seed is random in itself as evidenced by https://xkcd.com/221/
random.seed(seed)
for i in range(n-1):
x = random.random()
return random.randint(a, b)